javascript quiz 如何给答案数组一个默认值？

Question

我正在创建一个需要回答每个答案的测验。问题是如果您没有答案，您应该能够跳过问题。每次按下一步时，我都会尝试设置默认答案，因此当我尝试跳过一个时，我不必回答它即可获得价值。我想要的默认值是每次我数组的最后一个值。

下一个和上一个问题

        SetQuestion(question) {

            if (this.questionNumber >= 0) {
                let oldAnswerButton = document.querySelectorAll('.filter_anwser');

                // Deletes old question when the next question is clicked
                for (let answerButton of oldAnswerButton) {
                    answerButton.style.display = 'none';
                }
            }

            this.questionNumber = question;

            let q = this.quiz[question];
            // Check if your at the last question so the next button will stop being displayed.
            if (this.questionNumber === Quiz.length - 1) {
                this.nextbtn.style.display = 'none';
                this.prevbtn.style.display = 'block';
                this.resultbtn.style.display = 'grid';
            } else if (this.questionNumber === 0) {
                this.nextbtn.style.display = 'block';
                this.prevbtn.style.display = 'none';
                this.resultbtn.style.display = 'none';
            } else {
                this.nextbtn.style.display = 'block';
                this.prevbtn.style.display = 'block';
                this.resultbtn.style.display = 'none';
            }

            // Displays Question
            this.questionName.textContent = q.questionText;
            this.questionName.id = "questionID";

            return q;
            console.log(this.getLink())
            console.log(this.tmp)

        }

        IntoArray() {
            const UrlVar = new URLSearchParams(this.getLink())
            this.UrlArray = [...UrlVar.entries()].map(([key, values]) => (
                    {[key]: values.split(",")}
                )
            );
        }

        NextQuestion() {
            // let quizUrl = this.url[this.questionNumber];
            let question = this.SetQuestion(this.questionNumber + 1);
            let pre = question.prefix;
            let prefixEqual = pre.replace('=', '');
            let UrlArr = this.UrlArray;
            let UrlKeys = UrlArr.flatMap(Object.keys)
            let answers = question.chosenAnswer.slice(0, -1);

            this.clicked = true;

            // Displays answers of the questions
            for (let y = 0; y < answers.length; y++) {
                let item = answers[y];

                // Display answer buttons
                if (UrlKeys.includes(prefixEqual)) { 
                    console.log("exists");
                    let btn = document.querySelector('button[value="' + item.id + '"]');
                    btn.style.display = 'block';
                } else {
                    let btn = document.createElement('button');
                    btn.value = item.id;
                    btn.classList.add("filter_anwser", pre)
                    btn.id = 'answerbtn';
                    btn.textContent = item.name;
                    this.button.appendChild(btn);
                }

                // let quizUrl = control.url[control.questionNumber];
                // // console.log(this.tmp);
                // if (quizUrl === undefined) {
                //     quizUrl.push(question.prefix[y] + '');
                // }

                // if (quizUrl === undefined){
                //     this.tmp.push('');
                // }
            }


            this.IntoArray();
        }

        PrevQuestion() {
            let question = this.SetQuestion(this.questionNumber - 1);
            let answers = question.chosenAnswer.slice(0, -1);

            // Displays answers of the questions
            for (let y = 0; y < answers.length; y++) {
                let item = answers[y];

                // Display answer buttons
                let btn = document.querySelector('button[value="' + item.id + '"]');
                btn.style.display = 'block';
            }
            this.IntoArray();
        }

链接创建者：

        /**
         * Returns the parameters for the URL.
         *
         * @returns {string}
         */
        getLink() {
            this.tmp = [];
            for (let i = 0; i < this.url.length; i++) {
                // Check if question is from the same quiz part and adds a , between chosen answers and add the right prefix at the beginning
                if (this.url[i].length > 0) {
                    this.tmp.push("" + Quiz[i].prefix + this.url[i].join(","))
                    // console.log(this.url)
                }
                if (this.url[i].length === 0) {
                    this.tmp.push("");
                }
            }
            /// If answers are from different quiz parts add a & between answers.
            return "" + this.tmp.join("&");
            // console.log(this.url[i].prefix);
        };

应答点击事件

    control.button.addEventListener("click", function (e) {
        const tgt = e.target;
        control.clicked = true;

        // clear the url array if there's nothing clicked
        if (control.url.length === control.questionNumber) {
            control.url.push([]);
        }

        let quizUrl = control.url[control.questionNumber];

        // Check if a button is clicked. Changes color and adds value to the url array.
        if (quizUrl.indexOf(tgt.value) === -1) {
            quizUrl.push(tgt.value);
            e.target.style.backgroundColor = "orange";
            // Check if a button is clicked again. If clicked again changes color back and deletes value in the url array.
        } else {
            quizUrl.splice(quizUrl.indexOf(tgt.value), 1);
            e.target.style.backgroundColor = "white";
        }

        console.log(control.getLink());
        console.log(quizUrl)

    })

数组：

    class QuizPart {
        constructor(questionText, chosenAnswer, prefix, questionDescription) {
            this.questionText = questionText;
            this.chosenAnswer = chosenAnswer;
            this.prefix = prefix;
            this.questionDescription = questionDescription;
        }
    }

    class ChosenAnswer {
        constructor(id, name) {
            this.id = id;
            this.name = name;
        }
    }

    let Quiz = [
        new QuizPart('Whats your size?', [
                new ChosenAnswer('6595', '41'),
                new ChosenAnswer('6598', '42'),
                new ChosenAnswer('6601', '43'),
                new ChosenAnswer('', ''),
            ], 'bd_shoe_size_ids=',
            'The size of your shoes is very important. If you have the wrong size, they wont fit.'),

        new QuizPart('What color would you like?', [
                new ChosenAnswer('6053', 'Red'),
                new ChosenAnswer('6044', 'Blue'),
                new ChosenAnswer('6056', 'Yellow'),
                new ChosenAnswer('6048', 'Green'),
                new ChosenAnswer('', ''),
            ], 'color_ids=',
            'Color isn t that important, It looks good tho.'),

        new QuizPart('What brand would you like?', [
                new ChosenAnswer('5805', 'Adidas'),
                new ChosenAnswer('5866', 'Nike'),
                new ChosenAnswer('5875', 'Puma'),
                new ChosenAnswer('', ''),
            ], 'manufacturer_ids=',
            'Brand is less important. Its just your own preference'),
    ]

我尝试为数组的链接创建者和我的事件侦听器提供一个默认值，并在我从我的一个按钮获得实际值时替换它，但它只是不起作用。有人可以帮帮我吗？

Answer 1

我知道，这可能与您对答案的期望相差甚远 - 但是您为什么不看看像 Vue 这样的响应式工具呢？它拥有完成此类任务可能需要的所有工具，甚至更多：

• 可以将整个测验抽象为一组简单的对象（问题）
• 下一个，上一个，设置默认答案变得轻而易举
• 易于扩展（带问题）
• 易于更新（模板、功能等）

Vue.component('QuizQuestion', {
  props: ['data', 'selected'],
  computed: {
    valSelected: {
      get() {
        return this.selected
      },
      set(val) {
        this.$emit('update:selected', val)
      }
    },
  },
  template: `
    <div>
      {{ data.text }}<br />
      {{ data.description }}<br />
      <div class="quiz-options">
        <label
          v-for="val in data.options"
          :key="val[0]"
        >
          <input
            type="radio"
            :name="data.text"
            :value="val"
            v-model="valSelected"
          />
          {{ val[1] }}
        </label>
      </div>
    </div>
  `
})
new Vue({
  el: "#app",
  computed: {
    currentQuestion() {
      return this.questions[this.current]
    },
    hasPrev() {
      return !!this.current
    },
    hasNext() {
      return this.current < this.questions.length - 1
    },
  },
  data() {
    return {
      current: 0,
      questions: [{
        text: 'Whats your size?',
        description: 'The size of your shoes is very important. If you have the wrong size, they wont fit.',
        options: [
          ['6595', '41'],
          ['6598', '42'],
          ['6601', '43'],
          ['', ''],
        ],
        selected: null,
      }, {
        text: 'What color would you like?',
        description: 'Color isn\'t that important, It looks good tho.',
        options: [
          ['6053', 'Red'],
          ['6044', 'Blue'],
          ['6056', 'Yellow'],
          ['6048', 'Green'],
          ['', ''],
        ],
        selected: null,
      }, {
        text: 'What brand would you like?',
        description: 'Brand is less important. Its just your own preference',
        options: [
          ['5805', 'Adidas'],
          ['5866', 'Nike'],
          ['5875', 'Puma'],
          ['', ''],
        ],
        selected: null,
      }, ],
    }
  },
  methods: {
    selectDefault() {
      this.questions[this.current] = {
        ...this.questions[this.current],
        selected: this.questions[this.current].options.slice(-1)[0],
      }
    },
    getPrev() {
      if (this.hasPrev) {
        if (!this.currentQuestion.selected) {
          this.selectDefault()
        }
        this.current -= 1
      }
    },
    getNext() {
      if (this.hasNext) {
        if (!this.currentQuestion.selected) {
          this.selectDefault()
        }
        this.current += 1
      }
    },
  },
  template: `
    <div>
      <quiz-question
        :data="currentQuestion"
        :selected.sync="currentQuestion.selected"
      /><br />
      <button v-if="hasPrev" @click="getPrev">PREV</button>
      <button v-if="hasNext" @click="getNext">NEXT</button>
      <button v-if="!hasNext">RESULT</button>
    </div>
  `
})

.quiz-options {
  display: flex;
  flex-direction: column;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app"></div>

编辑

但是，如果不使用框架/库，这里有一个更 OOP 的方法：

class Quiz {
  constructor(questions) {
    this._current = 0
    this._questions = questions
  }
  get current() {
    return this._current
  }
  set current(val) {
    this._current = val
  }
  get hasNext() {
    return this.current < this.questions.length - 1
  }
  get hasPrev() {
    return !!this.current
  }
  get questions() {
    return this._questions
  }
  get next() {
    this.current = this.hasNext ? this.current + 1 : this.current
    return this.currentQuestion
  }
  get prev() {
    this.current = this.hasPrev ? this.current - 1 : this.current
    return this.currentQuestion
  }
  get currentQuestion() {
    return this.questions[this.current]
  }
}

class Question {
  constructor({
    text,
    description,
    options,
    prefix,
  }) {
    this.text = text
    this.desc = description
    this.prefix = prefix
    this._options = options.map(([key, val]) => ({
      id: key,
      value: [key, val],
      selected: false,
    }))
  }
  get options() {
    return this._options
  }
  set options(newOptions) {
    this._options = newOptions
  }
  get selected() {
    return this.options.find(({
      selected
    }) => !!selected)
  }
  set selected(selectedVal) {
    this.options = [...this.options.map(({
      value: [key, val],
      selected,
      ...rest
    }) => {
      return {
        ...rest,
        value: [key, val],
        selected: key === selectedVal
      }
    })]
  }
  get lastOption() {
    return this.options.slice(-1)[0]
  }
  setDefault() {
    if (!this.selected) {
      this.selected = this.lastOption.id
    }
  }
}

const urlParser = (quiz) => {
  return quiz.questions.map(({
    prefix,
    selected = {
      value: ['']
    }
  }) => {
    const s = selected.value[0] ? selected.value[0] : ''
    return `${prefix}${s}`
  }).join('&')
}

const qArr = [{
    text: 'text1',
    description: 'desc1',
    options: [
      ['1_1', '11'],
      ['1_2', '12'],
      ['1_3', '13'],
    ],
    prefix: 'prefix_1_',
  },
  {
    text: 'text2',
    description: 'desc2',
    options: [
      ['2_1', '21'],
      ['2_2', '22'],
      ['2_3', '23'],
    ],
    prefix: 'prefix_2_',
  },
  {
    text: 'text3',
    description: 'desc3',
    options: [
      ['3_1', '31'],
      ['3_2', '32'],
      ['3_3', '33'],
    ],
    prefix: 'prefix_3_',
  },
]

const getOptionsHtml = ({
  text,
  options
}) => {
  let html = ''
  options.forEach(({
    id,
    value,
    selected
  }, i) => {
    html += `
        <label>
        <input
            class="question-input"
            type="radio"
          name="${text}"
          value="${value[0]}"
          ${selected ? 'checked' : ''}
        />
        ${value[1]}
      </label>
    `
  })
  return html
}

const getSingleQuestionHtml = (q) => {
  const optionsHtml = getOptionsHtml({
    text: q.text,
    options: q.options
  })
  return `
    ${q.text}<br />
    ${q.desc}<br />
    ${optionsHtml}
  `
}

const registerEventHandlers = ({
  container,
  question
}) => {
  const radioBtns = document.querySelectorAll('.question-input')
  radioBtns.forEach((input, i) => {
    input.addEventListener('change', function(e) {
      question.selected = e.target.value
    })
  })
}

const updateHtml = ({
  container,
  question
}) => {
  container.innerHTML = getSingleQuestionHtml(question)
  registerEventHandlers({
    container,
    question
  })
};

const updateContainer = (container) => (question) => updateHtml({
  container,
  question
});

const setElDisplay = ({
  el,
  display
}) => {
  if (display) {
    el.classList.add("d-inline-block")
    el.classList.remove("d-none")
  } else {
    el.classList.remove("d-inline-block")
    el.classList.add("d-none")
  }
}

const updateBtnVisibility = ({
  btnNext,
  btnPrev,
  btnResult,
  quiz
}) => () => {
  setElDisplay({
    el: btnNext,
    display: quiz.hasNext
  })
  setElDisplay({
    el: btnResult,
    display: !quiz.hasNext
  })
  setElDisplay({
    el: btnPrev,
    display: quiz.hasPrev
  })
}

(function() {
  const quiz = new Quiz(qArr.map(q => new Question(q)))

  const container = document.getElementById('quiz-container')
  updateQuizContainer = updateContainer(container)
  updateQuizContainer(quiz.currentQuestion)

  const btnPrev = document.getElementById('btn-prev')
  const btnNext = document.getElementById('btn-next')
  const btnResult = document.getElementById('btn-result')

  const updateBtns = updateBtnVisibility({
    btnPrev,
    btnNext,
    btnResult,
    quiz
  })
  updateBtns()

  btnPrev.addEventListener('click', function() {
    if (quiz.hasPrev) {
      quiz.currentQuestion.setDefault()
    }
    updateQuizContainer(quiz.prev)
    updateBtns()
  })
  btnNext.addEventListener('click', () => {
    if (quiz.hasNext) {
      quiz.currentQuestion.setDefault()
    }
    updateQuizContainer(quiz.next)
    updateBtns()
  })
  btnResult.addEventListener('click', function() {
    quiz.currentQuestion.setDefault()
    console.log(urlParser(quiz))
  })
})();

.d-inline-block {
  display: inline-block;
}

.d-none {
  display: none;
}

<div id="quiz-container"></div>
<div id="quiz-controls">
  <button id="btn-prev" class="d-inline-block">
    PREV
  </button>
  <button id="btn-next" class="d-inline-block">
    NEXT
  </button>
  <button id="btn-result" class="d-none">
    RESULT
  </button>
</div>
<div id="result"></div>